Technology / Computers

I’m beginning to suspect my computer does more good for the world the less I use it. During the day, I pound away at my keyboard—writing prose, sending e-mail, surfing through my usual routine of Web sites. But at night, as I sleep soundly in the other room, my computer works steadily in the darkness, trying to find a cure for smallpox.

Of course, buying and housing a million ordinary PCs is prohibitively expensive. The idea of distributed computing is to borrow processing power at no cost. Even the busiest home or office computer usually spends several hours a day doing nothing, and most everyday digital tasks—sending e-mail or surfing the Web—only tap a fraction of the processing power of today’s machines. Almost every second of every day home computers are wasting processing cycles that could be crucial to solving someone else’s problem. Thanks to distributed computing, those cycles need not go to waste anymore. As with your old winter jacket or unused furniture, you can now donate your computer’s spare time to a worthy cause.

For a distributed-computing project to work, you first need a problem that can be broken up into many computational pieces, each of which can be dispatched to a separate machine for processing in parallel. The most widely celebrated use of the technology is the SETI@home project, which analyzes radio signals from the Arecibo telescope in search of signs of extraterrestrial life. In the SETI project, each participating computer downloads data recorded from a small patch of the sky and analyzes it for unusual patterns that might distinguish intelligent life from the normal background noise of the universe.

If your pet causes are more down-to-earth, however, you need not donate your spare cycles to the search for aliens. Since the launch of SETI@home, various other computing projects have emerged, ranging from the search for molecular keys to pick the locks of deadly diseases to collaborative art projects that digitally mimic the process of natural selection.

Signing up for a distributed-computing project is simple. You download a small application, which looks superficially like a run-of-the-mill screen saver. Then you instruct the program how long to wait after you’ve stopped working before the screen saver launches and triggers a request to a central computer for something to work on. Depending on the speed of your computer and how much time it spends moonlighting, the micropuzzle might take minutes or weeks to solve. From the central computer’s point of view, this variability isn’t a problem; during that time, thousands or millions of other machines will be working on related micropuzzles.

As long as you’ve installed the program correctly, by nightfall you’ll be saving more than just your screen. Without lifting a finger, you may actually be helping to save the world. The smallpox research project that my computer participates in is hosted by a for-profit company named United Devices that sells its grid-computing expertise to businesses. But the company also runs a number of charitable projects in collaboration with universities and government agencies at a site called grid.org. So far 2.5 million computers have been enlisted for an omnibus effort to discover promising drug formulations for the treatment of cancer, anthrax, and smallpox.

Ed Hubbard, the president and founder of United Devices, says the smallpox research has been the most fruitful to date. “Imagine a square hole. That’s the surface site on the smallpox virus that we’d like to dock a small molecule into,” Hubbard explains. “Because if you do, you’ll stop it from reproducing. That’d be a great oral drug, because right now the only cure for smallpox is surviving it, unless you catch it in the incubation period when there are no symptoms.” The problem with docking that molecule is the number of interactions that go into making a perfect fit. Each compound being studied has a complex three-dimensional structure that interacts in unique ways with the target protein in the smallpox virus. “At a minimum we’re screening about 350 million interactions,” Hubbard says. “So it’s a huge number.”